AOL is cheating on its partner, InterActiveCorp’s Match.com, using – what else? – an online dating service.

America Online announced yesterday that it was launching Love.com, an Internet personals site that will compete with Match.com, the market leader. But Match.com still has a long-term contract to provide dating content within AOL’s subscription service.

“In the media business, players like ourselves and InterActiveCorp are familiar with this phenomenon,” said Steven McArthur, executive vice president for AOL messaging. “Sometimes you’re partners, sometimes you’re competitors.”

Familiar, but not always friendly. Tim Sullivan, president of Match.com, predicted that Love.com would fail, leaving AOL to woo back its spurned bedmate.

Sullivan said that AOL approached Match.com nearly a year ago about partnering on the Web, “but the structure of the relationship was not one that was interesting to us.” AOL then contacted other companies about helping to set up Love.com.

“I think they’re making a mistake,” Sullivan added. “I think they’d be better off working with us.”

With 910,000 paying customers, Match.com is the most popular service in the burgeoning online dating field. Subscribers pay anywhere from $11 to $20 a month to browse Web ads and contact potential mates.

But the market is growing so quickly that everyone from Yahoo! to Friendster to a host of other companies have entered the singles bar.

Surfers spent $214.3 million on personals in the first half of this year, up 7.6 percent from 2002, according to the Online Publishers Association.

Love.com will be free through Valentine’s Day, after which AOL plans to introduce some subscription fees, McArthur said.

Both AOL and Match.com officials said that, despite the new service, there were no plans to terminate their partnership. InterActiveCorp stock continued its month-long slide yesterday, closing down 69 cents a share to $28.79.